Turbulent Times

August 2010 A stewardess was thrown into the air as her Scandinavian Airlines Boeing 737 hit turbulence approaching Heathrow airport in London. She badly injured her back and spent 10 days in hospital.

July 2010 Thirty people were injured on a United Airlines flight travelling between Washington and Los Angeles. The plane landed at Denver where 21 people were treated in hospital. "The whole plane felt like it was dropping," said a passenger.

May 2010 Ten people were hurt when a United Airlines plane encountered turbulence en route from London to Los Angeles. It diverted to Montreal, where six people were taken to hospital.

February 2009 Nearly 50 people were hurt as a Northwest Airlines flight from Manila was nearing Tokyo. Most received head or neck injuries. "My whole body was lifted into the air," said one passenger.

Although some air pockets are difficult to predict, pilots know that black storm clouds ahead often mean severe shaking and low visibility, as well as possible hail and lightning.

To spot these hazards and make the correct decision about pressing ahead or deviating, most large commercial and business jets are equipped with weather radar systems.

Partly thanks to this technology, pilots are able to notice thunderstorms early - but people still end up getting hurt. Last year, 80 passengers and cabin crew had turbulence-related injuries on commercial UK aircraft, says the UK Civil Aviation Authority.

And according to the US Federal Aviation Administration (FAA), nearly 60 people are hurt each year because of turbulence on US flights - there have even been a small number of fatalities. Bad weather also accounts for 70% of flight delays.

“Start Quote

We interpret the image for the pilot, showing turbulence, hail and lightning icons”

End QuoteRatan KhatwaHoneywell

A dish attached to the plane's nose or one of the wings scans the airspace in front, and the pilot has to manually adjust the tilt to check the weather above or below.

When workload is high, it is possible to misadjust the radar or misinterpret the data.

This could lead to the plane flying right into a dangerous cell or deviating too much, using more fuel than necessary.

But the new developments could help solve these issues, says Philip Brown, a cloud physicist from the Met Office, the UK's national weather service.

Auto-tilt and auto-scan techniques could be "a significant advance in on-board data processing and display systems", he says.

"By doing a lot of data storage and processing, the system is able to generate displays that can be used more intuitively than those from standard aircraft weather radar displays."

One feature involves warning if rain might have interfered with the radar beams, creating a distorted reading.

The next-generation weather radars could help pilots more accurately predict weather conditions ahead

"This could certainly be a useful new feature in navigating around intense thunderstorm activity," says Mr Brown.

3D weather map

US-based Honeywell, one of the biggest global aviation suppliers, has just rolled out its next-generation Intuvue system.

It automatically scans above, below and in front of an aircraft, relying on sensors to determine moisture content, temperature profile and other data in the storm cell ahead.

On-board computers then access the "reasonable probability" of external hazards - and display a three-dimensional weather map for the pilot in real time, says the firm's senior chief engineer, Ratan Khatwa.

"We've simplified the operation - our new radar is hands-free.

Honeywell's new weather radar uses icons to display weather hazards

"Instead of asking the pilot to manipulate tilt, the radar antenna automatically scans the airspace up to 320 miles in front and up to 60,000ft in altitude - a range greater than any other radar that exists today.

"And we interpret the image for the pilot, showing turbulence, hail and lightning icons."

The new system is already installed on a number of US aircraft, he adds.

"We initially evaluate using horizontal 2D sweeps and develop the track information for up to 40 thunderstorm threats. Based on their relative threat to the aircraft, cells are then analysed individually using vertical sweeps.

"This allows us to concentrate on the individual threats and provide a real-time threat analysis.

"In the future, it will also be important for the on-board radar to be shared with air traffic controllers so everyone has a common weather picture."

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